That's a really tough decision to make. I only have one child, but I've seen my niece's response to a new sibling. Honestly, I'd keep DS in the same daycare. With the arrival of his sister, he'll have enough upheaval in his life. It would be nice for him to go back to something familiar when you go back to work.

Regarding the germs, there will be germs no matter what kind of childcare situation. My dd was in a small in-home childcare siuation and she caught all the bugs that the provider's older elementary age child brought home. It was no different from the Montessori that she attends now. By the time you go back to work, the weather will be warmer and cold/flu season will be waning.

__________________Weena,
wife to James and WOHM to Autumn (2.5)
Labels? I don't use labels. I can't even get my label maker to work.